I suppose the 2 cols (vertical and centered aligned) should fit with the window-height

Hi. Your assumption is not true. It does not work this way. To understand, you need to explore Flex Box CSS.

To get the result as you want, you need to use CSS code:

.sppb-container-inner, .sppb-container-inner > .sppb-row {
    height: 100%;
}

This is a general code. It will have an impact on all elements of the SP PB.

Use your unique class for section to make this code isolated. Exemple

.your-section-class .sppb-container-inner, 
.your-section-class .sppb-container-inner > .sppb-row {
    height: 100%;
}